At the present time, many attempts are being made to integrate high density, non-volatile magnetic memories with semiconductor devices. In particular, semiconductor devices, such as various CMOS circuits, can be used for switching and otherwise controlling arrays of high density, non-volatile magnetic memories. The CMOS circuits are highly desirable because of the low currents required and high efficiency.
However, CMOS fabrication processes require many high temperature processing steps (i.e., temperatures in excess of 800.degree. C.). After metal interconnect layers are deposited the CMOS processing steps are limited in temperature to around 500.degree. C. However, the deposition of dielectric and metal layers is improved at higher temperatures. Thus, it is desirable to use as high a temperatures as practical.
One problem in the integration of CMOS circuits with GMR memory devices is that giant magneto-resistive (GMR) materials used as memory elements are generally restricted to temperatures below 300.degree. C. in order to prevent intermixing of the GMR materials. Also, the GMR materials contain elements which oxidize readily and which are sensitive to corrosion. Thus, the GMR materials must be protected from processes that oxidize or contain corrosive agents to magnetic materials.
Accordingly it would be highly desirable to provide an improved method of fabricating memories containing GMR materials with CMOS circuits.
It is a purpose of the present invention to provide a new and improved method of fabricating memories containing GMR materials.
It is another purpose of the present invention to provide a new and improved method of fabricating memories containing GMR materials in which the magnetoresistive ratio of the GMR materials is maximized.
It is still another purpose of the present invention to provide a new and improved method of fabricating memories containing GMR materials in which the GMR materials are protected from oxidizing and corrosive materials.
It is a further purpose of the present invention to provide a new and improved method of fabricating memories containing GMR materials in which the GMR materials are protected from high temperatures and corrosive materials commonly utilized in CMOS manufacturing processes.